If your lab report says leukocytes in urine, or lists a WBC count under the urinalysis section, you are looking at white blood cells that showed up where there should be very few. It is one of the most common results patients bring to my office, and the first thing I tell them is this: it is a signal worth understanding, not a diagnosis on its own.
White blood cells in the urine usually mean there is inflammation somewhere along the urinary tract. Most of the time the cause is a urinary tract infection that responds well to treatment. Sometimes the cause is something else entirely, and sometimes the sample simply was not collected cleanly. The number by itself does not tell you which of those it is.
Below I explain what the values mean, what causes them to rise, and the specific situations where this result deserves a closer look at your kidneys.
The information here is educational and does not replace an evaluation by your own physician. Every case is different.
What leukocytes in urine actually are
Leukocytes are white blood cells, part of your immune system. They travel through the bloodstream and move into tissue wherever the body detects irritation or infection.
Urine that has passed through healthy kidneys, ureters, bladder and urethra normally carries almost none of them. When white blood cells appear in a urine sample in meaningful numbers, it tells us the immune system has been called to that area. The medical term for this is pyuria.
What that inflammation is responding to is the real question, and that is what the rest of the workup answers.
Reading the numbers on your report
Two different tests can flag this, and they show up differently on the page.
Microscopic examination reports white blood cells per high power field, written as WBC/hpf:
- 0 to 5 WBC/hpf is the range most laboratories consider normal
- Above 5 to 10 WBC/hpf is generally reported as pyuria
- Higher counts, sometimes described as “too numerous to count”, point to more active inflammation
Dipstick testing reports leukocyte esterase, an enzyme released by white blood cells. It is a screening test, so results read as negative, trace, small, moderate or large rather than as a number. A positive leukocyte esterase suggests white blood cells are present, but it should be confirmed by looking at the sample under the microscope.
You may also see nitrites on the same report. Certain bacteria, including E. coli, convert nitrates in urine into nitrites. When leukocyte esterase and nitrites are both positive, a bacterial infection becomes considerably more likely.
One caution about reference ranges: they vary slightly between laboratories, and the range printed on your own report is the one that applies to your result.
The most common causes
Urinary tract infection. This is the leading cause by a wide margin. Bacteria reach the bladder, the body responds, and white blood cells appear in the urine. It is far more frequent in women, because the urethra is shorter and bacteria have less distance to travel.
Kidney infection (pyelonephritis). When an infection moves up from the bladder to the kidney, the white blood cell count usually rises sharply and the person feels genuinely unwell, often with fever, chills and flank pain. This one needs prompt medical attention.
Sample contamination. More common than most people realize. Cells from the genital area can enter the cup and raise the count without any infection in the urinary tract at all. If your report also mentions squamous epithelial cells, contamination is a likely explanation, and the usual next step is simply to repeat the test with a clean catch midstream sample.
Kidney stones. A stone irritates the lining of the urinary tract as it moves, and that irritation alone draws white blood cells, with or without infection.
Recent instrumentation. A urinary catheter, a cystoscopy or a recent procedure can produce pyuria for several days afterward.
Intense exercise, dehydration or fever. These can raise the count transiently. A result found during an acute illness is worth repeating once you have recovered.
Sterile pyuria: white cells with no bacteria
Sometimes the microscope shows white blood cells but the urine culture grows nothing. This is called sterile pyuria, and it is the situation where I most often get involved, because the usual explanation has been ruled out and something else is driving the inflammation.
Causes worth investigating include:
- A partially treated infection, when antibiotics were started before the culture was collected
- Sexually transmitted infections, particularly chlamydia, which does not grow on a standard urine culture
- Interstitial nephritis, an inflammatory reaction in the kidney that is frequently triggered by a medication
- Kidney stones, which irritate without infecting
- Glomerular disease, inflammation of the kidney’s filtering units
- Urinary tract tuberculosis, uncommon but important not to miss when pyuria is persistent and cultures stay negative
The pattern that matters here is a culture that keeps coming back negative while the white blood cells keep coming back positive. That combination should not be dismissed.
Symptoms that change the picture
Leukocytes in urine are often found on a routine test in someone who feels perfectly fine. What you are experiencing alongside the result helps narrow things down considerably.
Symptoms that suggest a urinary tract infection:
- Burning or pain when urinating
- Needing to urinate frequently or urgently, often passing very little
- Cloudy urine, or a strong odor
- Pressure or discomfort low in the abdomen
Symptoms that suggest the kidney is involved and warrant prompt evaluation:
- Fever and chills
- Pain in the flank or mid back, usually on one side
- Nausea or vomiting
- Visible blood in the urine
And when there are no symptoms at all, the finding still deserves follow up, particularly if it persists across more than one test. Silent inflammation in the kidney is precisely the kind of thing that gets discovered late, and I would much rather look into it early.
How the cause gets identified
The workup is straightforward and follows the clues in order.
Urine culture identifies whether bacteria are present, which organism it is, and which antibiotics will work. It is the single most useful next test after an abnormal urinalysis.
Repeat urinalysis with a clean catch sample settles the contamination question, which resolves a good number of cases without anything further.
Blood tests, including creatinine and estimated glomerular filtration rate, show whether kidney function itself has been affected.
Urine protein testing matters a great deal. White blood cells together with protein in the urine shifts suspicion toward the kidney’s filters rather than the bladder.
Imaging, usually ultrasound or CT, looks for stones, obstruction or structural abnormalities when the picture does not fit a simple infection.
Targeted testing for chlamydia, tuberculosis or specific kidney conditions, when the history and the persistence of the finding point that way.
Treatment follows the cause
There is no treatment for “leukocytes in urine” as such, because the white blood cells are the response, not the problem. What gets treated is whatever provoked them.
A bacterial infection is treated with the antibiotic the culture indicates, for the full course prescribed. Stopping early because the burning improved is one of the most common reasons an infection returns.
A stone is managed according to its size and location. Interstitial nephritis often improves once the responsible medication is identified and stopped, which is a good reason to bring your complete medication list, including over the counter drugs and supplements, to your appointment. Glomerular disease requires specific treatment directed at the underlying condition.
And contamination requires nothing at all beyond a properly collected repeat sample.
I want to be direct about one thing: there is no home remedy or supplement that clears white blood cells from urine. Staying well hydrated supports urinary health and is worth doing, but it does not treat an infection or resolve inflammation of the kidney. Please do not delay evaluation while trying something over the counter.
Why persistent leukocytes matter for your kidneys
This is the part I care about most as a nephrologist.
A single urinary tract infection, properly treated, rarely leaves lasting damage. Repeated infections are a different story, especially when they reach the kidney. Each episode of pyelonephritis can leave scarring, and scarring is permanent. Enough of it, over enough years, reduces how well the kidneys filter.
Chronic inflammation that never gets a diagnosis carries the same risk through a different route. Interstitial nephritis that goes unrecognized because the trigger was never removed will keep doing damage quietly. Chronic kidney disease very often progresses without symptoms until a substantial share of function is already gone, which is exactly why a finding like this deserves an explanation rather than a wait and see approach.
Prevention is the whole point of catching it early. That is not a slogan; it is the practical difference between managing a treatable infection and managing kidney damage that will not reverse.
Reducing your risk
Sensible measures that genuinely help:
- Drink enough water through the day, so that urine stays light in color
- Do not hold urine for long stretches
- Urinate after sexual activity, which helps clear bacteria from the urethra
- Wipe front to back to reduce bacterial transfer
- Complete every antibiotic course exactly as prescribed
- Manage diabetes and blood pressure well, since both raise the risk of urinary infections and of kidney damage
- Review your medications periodically with your physician, particularly regular anti inflammatory use
When to see a nephrologist
Consider a kidney specialist when:
- The finding persists after treatment, or keeps returning
- Cultures are repeatedly negative while white blood cells remain present
- Protein or blood in the urine appears alongside it
- Creatinine is rising, or estimated filtration rate is falling
- You have diabetes, high blood pressure, lupus or another condition that affects the kidneys
- You have had several kidney infections
A single treated bladder infection does not require a nephrologist. A pattern does.
Talk to a nephrologist in Santo Domingo
I am Dr. Elizabeth Villanueva, a nephrologist and internist practicing in Santo Domingo, Dominican Republic. I see patients who arrive with a lab result they do not understand and a reasonable amount of worry attached to it, and much of my work is turning that into a clear explanation and a plan.
If your urinalysis shows leukocytes and no one has explained what is driving them, bring the report and any previous results to a consultation. Understanding a result is the first step toward doing something useful about it.